If you are serving people from all over the world. In terms of charges, ease of integration, setup, reporting, etc. etc.
Please include pros and cons while comparing. Expecting nice comparison between Paypal, Stripe, Braintree, Intuit, etc.
Stripe, hands down.<p>If you are just starting, go with Stripe because it's easy to get up and running and the documentation is great. And it's designed beautifully from the API to the dashboard. I want to work with companies that make great products and I'm happy to pay premium for that.<p>If you're looking to switch from an existing provider, you could make the decision based on who has the lowest rate, but unless you're doing over $1mm/yr the difference is only ~$1000. Hardly worth the time you'll spend.
Best is too difficult to quantify without parameters that matter. Stripe is almost certainly the easiest to integrate quickly, but is definitely not the cheapest. Paypal has perhaps the broadest reach to potential customers, but doesn't work for certain payment types. Braintree is perhaps the cheapest at scale, but is more complicated to set up and has monthly minimums, making it ill-suited for bursty vendors.<p>They're all good, and they're all likely to meet a given need, but it would be easier to give a better answer if you list your criteria. Otherwise, you might have better luck on Quora (or here, maybe?)